Interference theory - when two pieces of information disrupt each other which can result in forgetting one or both pieces of information, or distortion of memory.
Types of interference
Proactive interference -when an older memory interferes with a newer one.
Retroactive interference -when a newer memory interferes with an older one.
Interference is worse when the memories are similar (McGeogh & McDonald). They studied retroactive interference by changing the amount of similarity between two sets of materials. Participants had to learn a list of 10 words until they could remember them with 100% accuracy. They then learned a new list.
There were 6 groups of participants who had to learn different types of new lists:
synonyms
antonyms
words unrelated to originals
consonant syllables
3 digit numbers
no new list (control condition)
When the participants were asked to recall the original list Group 1 produced the worst recall. This shows that interference is strongest when memories are similar.
Explanation of the effects off similarity
The reason why similarly affects recall could be due to a
proactive interference where previous information could make it more difficult to store newer similar information.
or
a retroactive interference where new information overrides previous similar memories due to similarity.